The present invention relates to space heating apparatus and more particularly to an improved steady state fuel burner assembly for a heat exchanger and an improved method for operating such a burner assembly.
It long has been known in the art of space heating to intermittently throttle or shut-off the flow of fuel and/or air through valve control means responsive to intermittent pressure pulses in the combustion chamber of a pulse type space heater. In this regard, a number of U.S. and foreign patents have been directed toward and disclose pulse type space heaters which utilize unique pulse enhancing valve arrangements in controlling air and/or fuel flow to a pulsing combustion chamber. For example, attention is specifically directed to U.S. Pats. No. 2,898,978, issued to J. A. Kitchen et al on Aug. 11, 1959; No. 4,457,690, issued to Toshihiko Saito et al on July 3, 1984; No. 4,457,691, issued to Satoshi Hissoka et al on July 3, 1984; No. 4,640,674, issued to John A. Kitchen on Feb. 3, 1987, and No. 4,687,435issued to Takashi Matsuzaka on Aug. 18, 1987. Attention is further directed to the Japanese patent publications EP 0066203 of Dec. 1982 to Tokyo Shibaura Denk and EP 0157372 of Oct. 1985 to Toshiba KK and to German Pat. No. 951829 to I. Holzapfel, published on Nov. 8, 1956. These foreign patent publications, like the aforenoted U.S. patents, also teach pulse enhancing valve control arrangements responsive to intermittent pressure pulses in a pulse type space heater to control the flow of fuel and/or air to the heater combustion chamber.
In accordance with the present invention, it is recognized that undesirable pulsation problems and flame-outs can occur in steady state fuel burner assemblies--as distinguished from the desirable pulsing which is sought in existing art pulse type heaters as above discussed. The present invention further recognizes that such undesirable pulsation with concomitantly undesirable effects on a steady, efficiently operating flame front is triggered by the high resistance to the flow of combustion products during start-up operations with the sudden expansion of the burning gases at the point of ignition resulting in undersirable flame front oscillations generally along the longitudinal axis of a typically cylindrical combustion chamber or in other directions depending upon the geometrical configuration of the combustion chamber. This undesirable pulsation and the resulting rapid flame front oscillation within the combustion chamber of steady state fuel burner assemblies tends to distort or to even extinguish the flame front since the initial explosion and pulsation blows away the supporting oxygen, thus furthering immediate demands for additional supporting oxygen to maintain the flame front and overcome heat exchanger resistance. This, in turn, has led to further pulsation and inefficient heating operations along with undesirable deposition of carbon materials adjacent the burner assembly inlets in establishing the burner assembly flame front and burner assembly pressure equilibrium. The present invention, recognizing the desirability and importance of promptly establishing flame front equilibrium and stability with concomitant high operating efficiency within the burner assembly and a minimum of carbon deposition, accomplishes the same in a straightforward and efficient manner with a minimum of manufacturing and assembly parts, improving the overall operation of a steady state fuel burner assembly as well as the space heater with which it is associated.
More specifically, the present invention provides a unique valve control mechanism in a space heater fuel burner assembly and method of operation which includes the instant blocking of the reverse flow of the products of combustion of a fuel and air mixture upon ignition. As a consequence, the products of combustion escape downstream from the combustion chamber and heat exchanger to quickly reach an equilibrium pressure normal to steady state combustion, providing an ideal environment for fuel combustion.
Various other features of the present invention will become obvious to one skilled in the art upon reading the disclosure set forth herein.